Monday, August 17, 2009

Welcome to the first week of LSAT Statistics!

For the next two weeks Zen of 180 will be examining all manner of interesting and relevant statistics about the LSAT, including today: "How many people score a perfect 180 on the LSAT?"

Last year, about 30 people--or 0.02% of people who sat for the LSAT--scored a 180.

All of the data taken for this series of articles are gleaned from lsacnet.org, the research division of the Law School Admissions Council. While many of the data is available in downloadable .pdfs, it is in messy tables, boring graphs, and not built to easily answer the questions that people have while preparing for the LSAT.

Today we'll start with one of the most common questions: "How many people score [the score I need] on the LSAT." We re-analyzed data compiled by LSAC between 1997 and 2004--the most recent they have published--in order to answer this question. We'll discuss this in more detail tomorrow, but by simply multiplying the percentage of a scale score allocated by the bell-curve distribution, we found the number of test-takers who earned each individual score from 160-180. It's worth noting that this is not the number of people who scored higher or lower than the scale score--which is often how a scale score is reported, i.e. "I scored better than 99.2% of test-takers"--rather, it is the estimated number of people who actually saw that score on their LSAC report.



Also, people often ask how the 99th percentile of the LSAT scale score is determined, since it's cited as a cut-off for the top law schools.

The 99th percentile--the scale score at which a test-taker has scored more points than 99% of all other test-takers--is usually distributed on the bell curve around 172. We zoomed in within that 99th percentile to show you how cumulatively adding the number of people with scores from 180-172 breaks the 99th percentile barrier. Essentially, when you add the test-takers who scored a 180 to the ones who scored 179, 178, etc, the subtotal becomes 1% of the overall when the 172 people are added.


For example, someone who scored a 178 is in the top 99.95% of LSAT test-takers, only .05% of people--those who scored a 179 or 180--are in front of them.

A score of 177 is in the top 99.85% of LSAT test-takers, with only those who scored a 178, 179, or 180 ahead of them.